Boiler shows E09 and will not fire; may be accompanied by low system pressure reading.
Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
Possible Causes
How to Fix / Troubleshooting
Safety: Do not over-pressurize the system. Typical cold fill pressure is around 12–20 psi depending on building height. Check the IBC manual for exact values.
- Check pressure gauge: Read the boiler's digital or analog pressure indication. If below the minimum (often ~10–12 psi), the system needs water.
- Open fill valve: Locate the automatic fill valve or manual feed valve to the boiler. Slowly open it and watch the pressure rise. Close the valve when the correct pressure is reached.
- Bleed air: After filling, bleed air from radiators or air vents and recheck pressure, topping up as needed.
- Inspect for leaks: Look around the boiler, near relief valves, and at visible piping for signs of water leakage.
- Reset: Once pressure is correct and stable, reset the boiler and confirm E09 clears.
If the pressure is normal but E09 remains, the system pressure sensor or switch may be defective and should be tested and replaced by a technician.
Repair Difficulty
Required Part
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